1. Technical Field
The present invention relates to a battery device, particularly to the one including a photoelectric conversion device and a secondary battery combined therein, as well as to an apparatus including such battery device.
2. Related Art
In order to construct a solar cell (photoelectric converter) system, a secondary battery is necessary for accumulating the electricity generated by the solar cell.
The problem inherent in using the secondary batteries is that the secondary batteries are arranged separately from the solar cell in a different place, thereby requiring securing a designated space for them, making the system less mobile.
An example of a structure that resolves such problem is disclosed in JP-A-8-330616. In this example, the secondary battery and an amorphous silicon solar cell are combined and coupled in parallel.
However, such solar cell system includes the following problems. The number of the secondary batteries as well as the number of the solar cells (i.e., the number of cell rows) needs to be adjusted in a way that the output voltage of the entire system can be configured to a required value. Secondly, the manufacturing cost increases, since the build-in potential of the P-N junction needs to be adjusted by techniques such as impurity doping in silicon, in order to adjust the open circuit voltage (Voc) of the amorphous silicon solar battery.
Moreover, a device is disclosed in “Tejima et al, ‘Abstracts of the 2005 Fall Meeting of the Electrochemical Society of Japan’ (2005 nen denki kagaku gakkai shuki tailkai yokohsyu) 1E20, page 93”, the device in which a dye-sensitized solar cell and an electric double layer capacitor are adhered.
However, the device recited above is difficult to design, and is deficient in commercial viability, since the discharge capacity is 0.05 mAh/cm2 (extremely small) if the final voltage is 0.3V, and the since the discharge characteristics does not exhibit any range where the voltage value becomes flat.